Flareless well intervention

ABSTRACT

In an embodiment, a flareless well intervention method may involve cleaning a wellbore by introducing a working fluid into a wellbore, receiving the working fluid commingled with produced formation fluid, separating produced gas from the commingled fluid, and compressing at least a portion of the produced gas.

TECHNICAL FIELD

The present disclosure relates generally to oil and gas wellbore cleaning, and more particularly, to methods of handling gas produced thereby.

BACKGROUND

During well operations, solids may be introduced or encountered within the wellbore. These solids may include, but are not limited to, frac or isolation plugs (or parts thereof), frac balls, wellbore trash such as dropped objects or casing remnants, frac sand, produced solids, etc. In some applications, solids within the wellbore may obstruct or inhibit production or may damage components within the wellbore.

Therefore, it may be desirable at various times to remove these solids from the wellbore. In some applications, solids may be removed from a wellbore in preparation for completing the well and bringing in initial production, or to remove plugs to allow production from new frac zones or stages (i.e. a “drillout” procedure). Further, solids may be removed from an already completed wellbore (i.e. a “cleanout” procedure).

In some applications, solids can be removed from a wellbore by pumping a working fluid into the wellbore through a working string, displacing and moving the solids to the surface with the working fluid, cleaning the working fluid and separating the removed solids, and recycling the working fluid through the wellbore until the procedure is complete. In some applications, this process produces formation gas along with the solids and working fluid.

Conventionally, formation gas produced during a drillout or cleanout procedure must be released or flared off, despite its potential commercial value. Additionally, some jurisdictions strictly limit or impose penalties for release or flaring of such gas. Conventionally, therefore, operators must choose between more thorough drillouts and cleanouts, which may cause losses of viable product and/or environmental penalties, and more conservative drillouts and cleanouts, which may underperform or fail to accomplish the operator's goal entirely.

SUMMARY

In one embodiment, a flareless well intervention method may involve cleaning a wellbore by introducing a working fluid into a wellbore, receiving the working fluid commingled with produced formation fluid, separating produced gas from the commingled fluid, and compressing at least a portion of the produced gas.

BRIEF DESCRIPTION OF THE DRAWING

The accompanying drawings, which are included to provide further understanding and are incorporated in and constitute part of this specification, illustrate disclosed embodiments and, together with the description, serve to explain the principles of the disclosed embodiments. In the drawings:

FIG. 1 is a schematic diagram of a flareless well intervention system, in accordance with embodiments of the present disclosure.

FIG. 2 is a cross-sectional diagram of a cased wellbore with solids, in accordance with embodiments of the present disclosure.

FIG. 3 is a cross-sectional diagram of a cased wellbore with a working string inserted, in accordance with embodiments of the present disclosure.

FIG. 4 is a cross-sectional diagram of a cased wellbore with a working string inserted and with working fluid being introduced into the working string, in accordance with embodiments of the present disclosure.

FIG. 5 is a cross-sectional diagram of a cased wellbore with a working string inserted and with working fluid, solids, and formation fluids being produced via the annulus, in accordance with embodiments of the present disclosure.

FIG. 6 is a schematic diagram of a solids handling component, in accordance with embodiments of the present disclosure.

FIG. 7 is a schematic diagram of a phase separation vessel, in accordance with embodiments of the present disclosure.

FIG. 8 is a schematic diagram of a gas analysis device, in accordance with embodiments of the present disclosure.

FIG. 9 is a schematic diagram of a compressor, gas storage vessel, and a generator, in accordance with embodiments of the present disclosure.

FIG. 10 is a schematic diagram of a compressor and a pipeline, in accordance with embodiments of the present disclosure.

FIG. 11 is a schematic diagram of a particulate/working fluid separator and solids container, in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure relates generally to oil and gas wellbore cleaning, and more particularly, to methods of handling gas produced thereby. As described herein, embodiments of the method described herein address the issues described with respect to certain conventional processes.

In certain conventional applications, wells may produce substantial amounts of formation gas during a drillout or cleanout procedure. The produced formation gas may be commingled with the returned working fluid and solids.

In some applications, it may be desirable to perform a drillout or cleanout procedure under “underbalanced” conditions. During an underbalanced drillout or cleanout, the pressure in the wellbore is lower than the static pressure of the formation, which may result in increased removal of solids from the wellbore and better performance compared to certain other conventional procedures. However, performing a drillout or cleanout procedure under underbalanced conditions may also result in the production of substantially more formation gas. As noted above, production of formation gas during drillout or cleanout procedures may result in the loss (e.g., through flaring) of commercially valuable resources and/or environmental or regulatory problems.

Therefore, in accordance with the present disclosure, it is advantageous to provide a system or method to perform well cleaning procedures, including underbalanced well cleaning procedures, such as drillouts or cleanouts, that separate, capture, and compress produced formation gas. The disclosed system and methods allow for the captured formation gas to be stored, transported, utilized, and/or offered for sale.

Embodiments of the flareless well intervention system and method are described herein.

FIG. 1 is a schematic diagram of a flareless well intervention system 100 in accordance with embodiments of the present disclosure. With reference to FIG. 1 , the flareless well intervention system 100 can facilitate cleaning operations (such as drillouts and/or cleanouts) in the wellbore 102 and capture resulting produced gas 116 to prevent or minimize release or flaring of the produced gas 116.

With reference to FIG. 2 , particulates 122 and/or large solids 128 may be encountered in the wellbore 102. In some applications, solids within the wellbore 102 may obstruct or inhibit production, for example, by clogging perforations 130 and impeding formation fluid 129 from entering the wellbore 102 from the productive formation 127. Additionally, these solids may damage components within the wellbore 102. Therefore, in some applications, drillouts and/or cleanouts may be desired to remove these solids.

With reference to FIG. 3 , during a wellbore cleaning operation, the working string 101 is introduced into the wellbore 102 and lowered to a point where particulates 122 and/or large solids 128 may be encountered. The working string 101 can be introduced by a coiled tubing unit, a workover rig, or any other suitable working string management equipment disposed at the wellbore 102. In some embodiments (e.g. for drillouts), the working string 101 is a length of pipe that is smaller in diameter than the inner diameter of the wellbore 102. In other embodiments, (e.g. for cleanouts), the working string 101 is a length of pipe that is smaller in diameter than the casing disposed in the completed wellbore 102.

With reference to FIGS. 4 and 5 , in the depicted example, working fluid 112 is pumped down the working string 101 and into the wellbore 102 via the bottom of the working string 101. In some embodiments, the working fluid 112 passes through a tool, such as a mud motor and a bit, prior to entering the wellbore 102.

During operation, the working fluid 112 introduced into the wellbore 102 displaces and moves particulates 122 and large solids 128 within the wellbore 102 to the surface. As illustrated, the introduced working fluid 112 returns toward the surface via the annulus 131 defined as the space between the working string 101 and the wellbore 102 (or a casing disposed in the wellbore 102). As the working fluid 112 returns to the surface, the bulk movement of the working fluid 112 along with the specific gravity of the working fluid 112 move encountered solids toward the surface. Further, the bulk movement and specific gravity of the working fluid 112 also moves formation fluids 129 encountered in the wellbore 102 toward the surface. Therefore, working fluid 112, removed solids (large solids 128 such as broken drill bits and/or particulates 122 such as frac sand), liquids, and/or gases return to the surface as commingled annular returns 114. The commingled annular returns 114 may be single-phase or multi-phase.

In some embodiments, the working fluid 112 can be formulated and/or introduced in a manner to promote the removal of solids from the wellbore 102. In some applications, the working fluid 112 can be formulated to create an underbalanced condition in the wellbore 102, in which the pressure in the wellbore 102 is lower than the static pressure of the formation. In some applications, an operator can control the aggressiveness of the drillout or cleanout procedure by varying the hydraulic head pressure by varying the flow rate and/or density of the working fluid 112. In general, more aggressive procedures remove more solids but also produce more formation gas. For example, the working fluid 112 can be formulated to have a sufficiently low density or specific gravity, for example, a specific gravity that results in a hydraulic head pressure that is lower than the formation pressure, permitting the production of formation fluid 129. In the depicted example, the working fluid 112 can include water or a water-based slurry, or any other suitable fluid. In other applications, the working fluid 112 is pumped or introduced into the wellbore 102 at a lower pressure than the surrounding formation fluid 129, also causing an underbalanced condition in the wellbore 102. In some embodiments, the flareless well intervention system 100 may utilize a combination of certain working fluid 112 formulations and/or pumping pressures. Advantageously, an underbalanced condition can promote the production of hydrocarbons and/or other formation fluids 129, which can assist with the lifting or movement of solids through the wellbore 102, improving the performance of the drillout or cleanout. As described above, any produced hydrocarbons or formation fluids, including gases, can return to the surface as commingled annular returns 114.

With reference to FIGS. 1 and 6-11 , in the depicted example, the commingled annular returns 114 are processed to separate and remove components of the commingled annular returns 114 for further handling and to allow the working fluid 112 to be recycled for further operations. With reference to FIG. 6 , initially, the solids-handling component 103 captures and disposes of large solid pieces in the commingled annular returns 114. The solids-handling component 103 is sometimes referred to as a “plug catcher” or “trash catcher.”

With reference to FIG. 7 , after the large solids are removed from the commingled annular returns 114, a phase separation vessel 104 separates or removes the produced gas 116 from the remaining reduced-solids returns 115. In some embodiments, the phase separation vessel 104 retains the remaining reduced-solids returns 115 for a retention period to separate the produced gas 116 from the produced liquids and solids 121. The retention period can be selected or configured to provide a desired amount of separation between the produced gas 116 and the produced liquids and solids 121. Optionally, the remaining reduced-solids returns 115 can pass over sets of obstructions within the phase separation vessel 104 to “bust off” the produced gas 116 from the reduced-solids returns 115. As illustrated, the produced gas 116 and the produced liquids and solids 121 exit the phase separation vessel 104 via separate outlets.

Advantageously, instead of being flared or released, the produced gas 116 can be sold or used, as appropriate. With reference to FIG. 8 , in the depicted example, a gas analysis device 105 can detect, clean, and separate commercially viable gas 117. During operation, the gas analysis device 105 can detect heavier and lighter molecular components of the produced gas 116. Based on the detection of the molecular components of the produced gas 116, the gas analysis device 105 can separate the produced gas 116 into viable gas 117 and waste gas 118. In some embodiments, the gas analysis device 105 can clean the viable gas 117. Optionally, the waste gas 118 can be disposed via flaring device 106 or any other suitable method.

With reference to FIGS. 9-10 , in the depicted example, the viable gas 117 is compressed by a compressor 108 for storage, use, and/or sale. The compressor 108 can compress the viable gas 117 to a pressure suitable for storage, introduction into a pipeline 124, or for immediate use. As illustrated in FIG. 9 , the compressed gas 120 can be stored in a storage vessel 107. The storage vessel 107 may be removed from the wellsite for sale or storage. Further, in some embodiments, the compressed gas 120 can be directed to provide fuel to a local gas-powered device, such as a generator 126 or other suitable device. Compressed gas 120 can be provided directly from compressor 108 to generator 126 or, as shown in FIG. 9 , may be provided to generator 126 from storage vessel 107 as a separate flow of compressed gas 125. As illustrated in FIG. 10 , in some embodiments, the compressed gas 120 can be introduced into a pipeline 124 to be sold or offered for sale. Optionally, the flareless well intervention system 100 can monitor, track, or meter the amount or monetary value of gas introduced into the pipeline 124.

With reference to FIG. 11 , in the depicted example, particulates 122 are removed from the produced liquids and solids 121 via a particulate/working fluid separator 110 to allow the working fluid 112 to be reused or recycled for further operations. The particulate/working fluid separator 110 can include one or more of: a tank, a V-shaped inner compartment, a series of baffles, physical filters (e.g. mesh filters, screens), augers, pumps, water jets, weirs, hydrocyclones, and/or a shaker deck to separate the particulates 122 and the working fluid 112 from the produced liquids and solids 121. As illustrated, the particulates 122 and the working fluid 112 exit the particulate/working fluid separator 110 via separate outlets. Further, the separated particulates 122 can be stored in a pit or container 111 for later handling.

As illustrated, the working fluid 112 can be recycled into the wellbore for additional operations. In some embodiments, as shown in FIG. 1 , the flareless well intervention system 100 may gain excess working fluid 123 over the course of operation from the production of formation fluids during underbalanced operations. In some embodiments, excess working fluid 123 can be stored in pits or tanks 113.

It is understood that variations may be made in the foregoing without departing from the scope of the present disclosure. In several exemplary embodiments, the elements and teachings of the various illustrative exemplary embodiments may be combined in whole or in part in some or all of the illustrative exemplary embodiments. In addition, one or more of the elements and teachings of the various illustrative exemplary embodiments may be omitted, at least in part, and/or combined, at least in part, with one or more of the other elements and teachings of the various illustrative embodiments.

Any spatial references, such as, for example, “upper,” “lower,” “above,” “below,” “between,” “bottom,” “vertical,” “horizontal,” “angular,” “upwards,” “downwards,” “side-to-side,” “left-to-right,” “right-to-left,” “top-to-bottom,” “bottom-to-top,” “top,” “bottom,” “bottom-up,” “top-down,” etc., are for the purpose of illustration only and do not limit the specific orientation or location of the structure described above.

In several exemplary embodiments, while different steps, processes, and procedures are described as appearing as distinct acts, one or more of the steps, one or more of the processes, and/or one or more of the procedures may also be performed in different orders, simultaneously and/or sequentially. In several exemplary embodiments, the steps, processes, and/or procedures may be merged into one or more steps, processes and/or procedures.

In several exemplary embodiments, one or more of the operational steps in each embodiment may be omitted. Moreover, in some instances, some features of the present disclosure may be employed without a corresponding use of the other features. Moreover, one or more of the above-described embodiments and/or variations may be combined in whole or in part with any one or more of the other above-described embodiments and/or variations.

Although several exemplary embodiments have been described in detail above, the embodiments described are exemplary only and are not limiting, and those skilled in the art will readily appreciate that many other modifications, changes and/or substitutions are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of the present disclosure. Accordingly, all such modifications, changes, and/or substitutions are intended to be included within the scope of this disclosure as defined in the following claims. 

1. A method of cleaning a wellbore through a formation comprising formation fluid, the method comprising: after the wellbore has been drilled to a desired depth, inserting a working string into the wellbore, such that an annulus is formed between an outer surface of the working string and an inner surface of the wellbore; selecting a working fluid formulated to promote the removal of solids from the wellbore; pumping the working fluid through the working string and into the wellbore at a pressure sufficient to cause the working fluid to flow through the length of the working string and back to the surface through the annulus; receiving from the annulus a commingled annular return comprising solids from the wellbore, the returned working fluid, and produced formation fluid; separating a produced gas from the commingled annular return; and compressing at least a portion of the produced gas.
 2. The method of claim 1 further comprising: analysing the produced gas.
 3. The method of claim 2 further comprising: disposing of at least a portion of the produced gas via flare in response to analysing the produced gas.
 4. The method of claim 1 further comprising: cleaning at least a portion of the produced gas.
 5. The method of claim 1 further comprising: separating at least a portion of the produced gas by molecular structure.
 6. The method of claim 1 further comprising: storing at least a portion of the produced gas.
 7. The method of claim 1 further comprising: transporting at least a portion of the produced gas via pipeline.
 8. The method of claim 1 further comprising: offering to sell at least a portion of the produced gas.
 9. The method of claim 1 further comprising: providing at least a portion of the produced gas to a gas-powered device.
 10. The method of claim 1, wherein the working fluid is introduced into the wellbore prior to a wellbore completion process.
 11. The method of claim 1 wherein the working fluid is introduced into the wellbore after a wellbore completion process.
 12. The method of claim 1, wherein introducing the working fluid into the wellbore further comprises introducing the working fluid in a manner to cause an underbalanced condition in the wellbore.
 13. The method of claim 1, wherein the working fluid is formulated to have a specific gravity such that the step of introducing the working fluid into the wellbore results in an underbalanced condition in the wellbore.
 14. The method of claim 12, wherein the working fluid is introduced at a working fluid pressure lower than a formation fluid pressure of the wellbore.
 15. A method of cleaning a wellbore through a formation comprising formation fluid, the method comprising: after the wellbore has been drilled to a desired depth, inserting a working string into the wellbore, such that an annulus is formed between an outer surface of the working string and an inner surface of the wellbore; selecting a working fluid formulated to promote the removal of solids from the wellbore and to cause an underbalanced condition in the wellbore; pumping the working fluid through the working string and into the wellbore at a pressure sufficient to cause the working fluid to flow through the length of the working string and back to the surface through the annulus; receiving from the annulus a commingled annular return comprising solids fluid from the wellbore, the returned working fluid, and produced formation fluid; separating a produced gas from the commingled annular return; compressing at least a portion of the produced gas; and storing at least a portion of the produced gas or transporting at least a portion of the produced gas via pipeline.
 16. The method of claim 15 further comprising: analysing at least a portion of the produced gas.
 17. The method of claim 16 further comprising: disposing of at least a portion of the produced gas via flare in response to analysing the produced gas.
 18. The method of claim 15 further comprising: cleaning at least a portion of the produced gas.
 19. The method of claim 15 further comprising: separating at least a portion of the produced gas by molecular structure.
 20. (canceled) 